Monday, October 29, 2018

"Tier 3+" or "Tier 4-Ready" Data Centers?

This is usually found in some data center specifications: "Tier III+" or "Tier IV-Ready" *

Let's clarify: There is no such thing as "Tier III+" or "Tier IV-Ready" for large data centers. They are not granted by any organizations in data center / critical facilities like Uptime Institute or Telecommunications Industry Association (TIA) - ANSI/TIA-942 **.

* The latest TIER IV-Ready Certification by the Uptime Institute is designed for modular data centers which enjoy the same level of reliability and resiliency that they have in their larger data centers.

** The term ‘Tier’ was used in the ANSI/TIA-942 Standard until the ANSI/TIA-942: March-2014 edition. In the March 2014 edition the term ‘Tier’ has been replaced by either ‘Rated’ or ‘Rating’.

Recap (1) More about Data Center Tier Levels; and
(2) Data Center Tier Levels and Uptime

The Uptime Institute issues Tier Certificates (Constructed Facility and Design Documents) for data center infrastructure. When a data center is accredited as Tier III Constructed Facility, the infrastructure, at the time of the site visit and demonstrations, should be "Concurrently Maintainable" and N+1 (N means Utility Power) with 1 active + 1 alternate distribution paths (electrical power backbone) and 2 simultaneously active critical power distribution.

One of the major different between Tier III and Tier IV infrastructure is the requirement of Distribution Paths - Electrical Power Backbone. Tier IV facilities require 2N / 2N+1 which means 2 electrical power backbone should be simultaneously active. It is nearly double the infrastructure of Tier III.

Although the Uptime Institute Tier Standard or the TIA-942 Standard does not require dual feeds from different power companies to achieve Tier IV standard, is it worth to build a Tier IV data center in Hong Kong?

The situation is different. Electricity supply in Hong Kong is highly reliable, exceeding 99.999%. The two power companies, CLP and HK Electric have adequate capacity and backup in electricity generation and in the transmission and distribution networks, which assured robustness and reliability of supply. A number of high-tier data centers are being serves by two utility feeds from different substations of the same power company.


A Tier IV infrastructure is nearly double of the Tier III. Thus most of the large data centers in Hong Kong are usually Tier III but leave rooms / spaces for adding facilities and expansion if required in the future (ready / upgradable to Tier IV standard).

About us

SMA connects IT, Facilities and Design. For the other design considerations, please visit 

(1) Site Selection,
(2) Space Planning,
(3) Cooling,
(4) Redundancy,
(5) Fire Suppression,
(6) Meet Me Rooms,
(7) UPS Selection,
(8) Raised Floor,
(9) Code & Standards,
(10) Transformers and Harmonic Distortion,
(11) Multi-mode UPS Systems,
(12) Electrical Rooms,
(13) Generator Systems,
(14) Generator Fuel Systems, etc.

All topics focus on key components and provide technical advice and recommendations for designing a data center and critical facilities.

Strategic Media Asia (SMA) is one of the approved CPD course providers of the Chartered Institution of Building Services Engineers (CIBSE) UK. The team exists to provide an interactive environment and opportunities for members of ICT industry and facilities' engineers to exchange professional views and experience.